How to grow Your Own Spirulina,sell algae oil and other value-added products

This study is made in April 27, 2006

In this PAGE we will discuss a few promising physical and chemical technologies for the utilizationand conversion of CO2 from a power plant into viable economic products. This task has beenperformed as part of a broader effort to appreciate the global concerns of increasing atmosphericconcentrations of CO2 and particularly the role of the recovery and utilization of CO2 fromindustry. This project will be used in part towards development of a solution for optimal CO2utilization.Various existing and future utilization technologies were explored in this project for optimum CO2utilization. The main areas of interest were micro-algae biomass production (closed/pond andbioreactor production), supercritical CO2 extraction technology, fixation of CO2 into organiccompounds (production of various chemical products), and CO2 reforming of methane. Thefeasibility of these processes was evaluated according to their thermodynamics, energetics,production rates and yields, product values and economics.The value-added products that can be produced from these four main technologies are: biomass(high and low grade), biomass derived products (pharmaceutical, chemical or nutritional),synthesis gas (methanol, fuel and chemical production), specialty products (extracted usingsupercritical technology), organic carbonates (linear, cyclic or polycarbonates), carboxylates(formic acid, oxalic acid, etc), salicylic acid and urea.It should be noted that the amounts of CO2 consumed for making the chemical products arerelatively small, but the advantages of the value-added products and the environment friendlyprocessing plus the CO2 avoidance compared to the conventional energy intensive or hazardousprocesses make CO2 utilization an important option in CO2 management.In conclusion, there are various methods that can be employed to utilize the inherent value of CO2. Any of the methods proposed in this project can make use of CO2 to produce value-addedproducts in environmentally friendly ways.

Introduction to project

1.1 Problem statement

Can value be added to current processes or emerging technologies to generate valuable productsby the utilization of CO2

? Emphasis has been placed on value added products and processes andnot in the amount of CO2 utilized. The overall scheme for this project is shown in Figure 1.1.1.

2. Biological utilization2.1 Algal mass culture systems2.1.1 IntroductionCarbon dioxide from various industrial sources (power plants, chemical industries, etc) can beconverted to biomass using algal mass culture pond systems.The main advantage of using pond systems is that the technology is very well known and variouscommercial systems already exist. Algal pond systems are currently the most economic method toproduce biomass on a large scale. For the effective conversion of CO2 to biomass, studies have tobe conducted to define growth characteristics of various organisms (micro-algae and seaweed).

The products obtained from algal mass culture can be of very high value (for example,pharmaceutical or food grade

Micro-algae can be isolated from various diverse sources, including rivers, lakes, ponds, springs,soil, seawater, basically anywhere in the world. Effective CO2 fixating organisms must be selectedfrom these samples using various selective growth conditions (CO2 tolerance, temperature, etc).A few micro-algae species that are commercially used are discussed in Table 2.1.1.Microalgae and seaweed species must be selected that show optimum growth with CO2 as thecarbon source and that can be cultivated at moderate temperatures and pH. Some organismshave been isolated using flue gas, but studies to date have only been performed at a bench-scale(currently, no commercial ponds use flue gas). One of the major problems with using power plantflue gas, is the lowering of the pH of the pond due to NOx and SOx species present. The pH canbe controlled in a pond system by the addition of CaCO3. Two very promising organisms are

Chlorella sp.

(Figure 2.1.1) and

Spirulina platensis

(Figure 2.1.2).

Table 2.1.1: Various organisms used to produce biomass.

Microalgae

Description/growth parameters

Figure 2.1.2: Spirulina platensis.

Spirulina

is a multicellular, filamentousblue-green algae. Various commercial

Spirulina

production plants currently inoperation.

Growth rate

: 30 g/m2day dry weight.

Temperature

: Optimum 35 – 37 °C.

pH

: Very tolerable to pH change.

Chlorella

is a unicellular organism thatcan be found in almost any waterenvironment (fresh water and marine).

Figure 2.1.1: Chlorella fusca.

Growth rate

: 26 g/m2day dry weight.

Temperature

: 35 – 37 °C (dependingon specie).

pH

: Depends on specie.

Enteromorpha

is a marine seaweedthat can be grown in shallow ponds.9Very little agitation is needed.

Growth rate

: 28 g/m2day dry weight.

Temperature

: Optimum between 24 –33 °C.

pH

: Relative pH sensitive.Seaweed, when compared to other biomass production, has a higher growth rate and yield. Themajor advantage of seaweed biomass production is the amount of genera that are known and thatare currently being commercially grown.